1. Field of the Invention
This invention relates to a disposable, single use spray dispensing assembly adapted for detachable connection with a source of pressurized air for applying liquid material such as adhesives, coatings, sealants, solvents, penetrants, lubricants and the like.
2. Description of the Related Art
Conventional pressurized air spray dispenser assemblies for spraying liquid material often include a spray head having a control valve, and a container releasably connected to the spray head. Typically, the container is filled by the user with liquid material from a larger, bulk container. Next, the spray head is connected to the container as well as an air hose. After the spraying operation, the spray head is detached from the hose and the container is detached from the spray head, and often both the spray head and the container are then cleaned i preparation for the next spray operation.
Spray heads associated with conventional spray dispensing assemblies have relatively small passageways that are difficult to clean when used with certain material. Solvents may be used in some instances for cleaning, but many solvents are relatively expensive, hazardous and present disposal problems. Moreover, it is often difficult, if not impossible, to reuse conventional spray assemblies for spraying certain liquids such as adhesives that cure and cannot be subsequently removed by solvents.
U.S. Pat. No. 4,804,144, dated Feb. 14, 1989, describes a spray dispenser apparatus that includes a eductor assembly having a dip tube that extends into a screw top container. The eductor assembly, the container or both may be disconnected when desired from an air gun control handle for disposal. The container includes an upper threaded tubular projection initially sealed by a disk having a scored center portion that may be punched out for insertion of the dip tube and connection of the eductor assembly to the container.
However, the spray apparatus described in U.S. Pat. No. 4,804,144 is not entirely satisfactory when such a container is to be used as a shipping container for the liquid material and bears a label to identify the liquid contents, because of the possibility that the container may be refilled with another composition after dispensing the original contents. In such instances, the label no longer correctly identifies the contents of the container and may not sufficiently warn the operator of hazards associated with the new contents (a particular problem if the apparatus is used by more than one person). Further, if the container and the eductor assembly are not sufficiently cleaned between uses, the new liquid contents may be contaminated or react with small residual amounts of the liquid material that was originally packaged in the container.
U.S. Pat. Nos. 4,936,511 and 4,971,251, both of which are assigned to assignee of the present invention, describe a liquid spray gun assembly having a disposable, bag-like container that is non-releasably fixed to a spray nozzle assembly that, in turn, is adapted for detachable connection with a reusable air gun handle that includes a control valve. A rupturable barrier within the bag container prevents liquid materials from evaporating or leaking through the spray nozzle during transit. At the end of a work operation, the nozzle and attached bag container are removed from the handle and disposed, so that no cleaning is necessary.
However, shipping regulations in certain jurisdictions prevent or at least hinder shipping liquid material in bag-like containers if the liquid material include solvent or flammable compositions. Moreover, there is a continuing interest in reducing the expenses associated with spray nozzles and containers and the accompanying cost of filling the containers. As such, it is often prudent to consider the use of conventional liquid containers that are widely available and inexpensive to purchase and fill. Moreover, since the spray head is non-releasably fixed to the bag-like containers of the dispensing assemblies shown in U.S. Pat. Nos. 4,936,511 and 4,971,251, the entire assembly is typically disposed even when only a portion of the liquid contents in the bag have been dispensed once the material has set up or cured in the passages of the spray head.